Grammar Changes (pytorch#42076)

Summary:
Small grammatical updates.
![Screenshot (188)](https://user-images.githubusercontent.com/56619747/88471271-02723480-cf25-11ea-8fd1-ae98d5ebcc86.png)

Pull Request resolved: pytorch#42076

Reviewed By: mrshenli

Differential Revision: D22756651

Pulled By: ngimel

fbshipit-source-id: e810eb7397a5831d801348c8fff072854658830e

torch/__init__.py

@@ -1,7 +1,7 @@
 
 r"""
 The torch package contains data structures for multi-dimensional
-tensors. It also defines mathematical operations that can be performed over these tensors.
+tensors and defines mathematical operations over these tensors.
 Additionally, it provides many utilities for efficient serializing of
 Tensors and arbitrary types, and other useful utilities.